diff --git a/src/common.h b/src/common.h
deleted file mode 100644
index 8f8af8c..0000000
--- a/src/common.h
+++ /dev/null
@@ -1,13 +0,0 @@
-#ifndef COMMON_H
-#define COMMON_H
-
-
-#define CONCAT(x,y) _CONCAT(x,y)
-#define _CONCAT(x,y) (x##y)
-
-
-#define TOSTR(x) _TOSTR(x)
-#define _TOSTR(x) (#x)
-
-
-#endif /* COMMON_H */
diff --git a/src/icmd.c b/src/icmd.c
index 9d028dc..ef9a603 100644
--- a/src/icmd.c
+++ b/src/icmd.c
@@ -1,68 +1,172 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <unistd.h>
+#include <stdarg.h>
 #include <string.h>
 #include <limits.h>
+#include <errno.h>
+#include <dirent.h>
+#include <sys/types.h>
 
 #include "icmd.h"
-#include "common.h"
 
 
-#define ICMDS_SIZE                                  \
-    (sizeof(g_icmds) / sizeof(g_icmds[0]))
-
-#define ICMD(name)                                  \
-    {                                               \
-        .cmd = TOSTR(name),                         \
-        .len = sizeof(TOSTR(name))-1,               \
-        .func = CONCAT(icmd_, name),                \
-    }
+#define ICMDS_SIZE                             \
+        (sizeof(g_icmds) / sizeof(g_icmds[0])) \
 
 
-struct icmd g_icmds[] =
+#define ICMD(name)                             \
+        {                                      \
+                .cmd = #name,                  \
+                .len = sizeof(#name) - 1,      \
+                .func = icmd_##name,           \
+        }                                      \
+
+
+struct icmd
 {
-    ICMD(exit),
-    ICMD(cd),
-    ICMD(ls),
+        char *cmd;
+        int len;
+        int (*func)(int, char **);
+
+} g_icmds[] =
+{
+        ICMD(help),
+        ICMD(exit),
+        ICMD(cls),
+        ICMD(cd),
+        ICMD(ls),
 };
 
 
-int
-call_icmds(char *line)
+
+#define icmd_die(status, ...)                            \
+        {                                                \
+                _icmd_die(status, argv[0], __VA_ARGS__); \
+                return status;                           \
+        }                                                \
+
+
+static void
+_icmd_die(int status, char *func, char *format, ...)
 {
-    size_t i;
+        va_list args;
 
-    for (i = 0; i < ICMDS_SIZE; i++)
-    {
-        printf("cmp: '%s' : '%s' with len %d \n", g_icmds[i].cmd, line, g_icmds[i].len);
-        if (strncmp(g_icmds[i].cmd, line, g_icmds[i].len) == 0)
-            return g_icmds[i].func(line);
-    }
-
-    /* todo: find better way to signal this? */
-    /*       maybe return function pointer? */
-    return INT_MAX;
+        va_start(args, format);
+        if (status != 0)
+                printf("%s: Error: ", func);
+        vprintf(format, args);
+        if (status != 0)
+                putchar('!');
+        putchar('\n');
+        if (status < 0)
+                perror("Reason");
+        va_end(args);
 }
 
 
 int
-icmd_exit(char *line)
+call_icmd(int argc, char **argv)
 {
-    printf("exiting with reason: %s", line);
-    exit(0);
+        size_t i;
+
+        for (i = 0; i < ICMDS_SIZE; i++)
+                if (strncmp(g_icmds[i].cmd, argv[0], g_icmds[i].len) == 0)
+                        return g_icmds[i].func(argc, argv);
+
+        return INT_MAX;
 }
 
 
 int
-icmd_cd(char *line)
+icmd_help(int argc, char **argv)
 {
-    printf("I'm a cd! line: %s\n", line);
-    return 0;
+        size_t i;
+
+        puts(
+                "\n  psh  -  poor man's shell"
+                "\n                          "
+                "\n  internal commands:      "
+        );
+
+        for (i = 0; i < ICMDS_SIZE; i++)
+                printf("    - %s\n", g_icmds[i].cmd);
+
+        putchar('\n');
+
+        return 0;
 }
 
 
 int
-icmd_ls(char *line)
+icmd_exit(int argc, char **argv)
 {
-    printf("I'm a ls! line: %s\n", line);
-    return 1;
+        puts("good bye!");
+        exit(0);
+
+        return 0;
+}
+
+
+int
+icmd_cls(int argc, char **argv)
+{
+        int i = 24;
+
+        while (i--)
+                putchar('\n');
+
+        return 0;
+}
+
+
+int
+icmd_cd(int argc, char **argv)
+{
+        char def_path[] = ".";
+        char *path = def_path;
+
+        if (argc > 2)
+                icmd_die(1, "too many arguments given");
+
+        if (argc == 2)
+                path = argv[1];
+
+        if (chdir(path))
+                icmd_die(-1, "could not change directory");
+
+        return 0;
+}
+
+
+int
+icmd_ls(int argc, char **argv)
+{
+        char def_path[] = ".";
+        char *path = def_path;
+        struct dirent *d;
+        DIR *dir;
+        int i = 1;
+
+        if (argc > 1)
+                path = argv[1];
+
+        do
+        {
+                if ((dir = opendir(path)) == NULL)
+                        icmd_die(-1, "could not open directory '%s'", path);
+
+                puts(path);
+                while ((d = readdir(dir)) != NULL)
+                        /* don't print current directory '.' and parent directory '..' */
+                        if (!(d->d_name[0] == '.' && (d->d_name[1] == '\0' || d->d_name[1] == '.')))
+                                printf("  %s\n", d->d_name);
+
+                closedir(dir);
+                putchar('\n');
+                path = argv[++i];
+
+        } while (i < argc);
+
+        return 0;
 }
diff --git a/src/icmd.h b/src/icmd.h
index dc444a8..1cfe9d1 100644
--- a/src/icmd.h
+++ b/src/icmd.h
@@ -2,22 +2,16 @@
 #define ICMD_H
 
 
-struct icmd
-{
-    char *cmd;
-    int len;
-    int (*func)(char *);
-};
+/* API */
+int call_icmd(int argc, char **argv);
 
 
-/* interface */
-int call_icmds(char *line);
-
-
-/* internal commands as functions */
-int icmd_exit(char *line);
-int icmd_cd(char *line);
-int icmd_ls(char *line);
+/* internal commands */
+int icmd_help(int argc, char **argv);
+int icmd_exit(int argc, char **argv);
+int icmd_cls(int argc, char **argv);
+int icmd_cd(int argc, char **argv);
+int icmd_ls(int argc, char **argv);
 
 
 #endif /* ICMD_H */